Method of making secondary aromatic amines



Patented Nov. 1, 1932 UNITED STATES PAUL c. JONES, OE OU AHOGA FALLS,OHIO, AssIoNO fTo THE B. E. eoonn'ron 1 COMPANY, OF NEw YORK, N. Y.,CORPORATION e Ew ORK,

METHOD OE MAKING SECONDARY AEOMA'rIc -A1v'rINEs No Drawing.

This invention relates'to theart of manufacturing organic chemicals andhas as its object to provide an improved method for 5 the manufacture ofsecondary aromatic amines, such as the di-aryl p-phenylene diamines.

I-Ieretofore symmetrical di-beta-naphthyl p-phenylene diamine has beenmade by heating p-phenylene diamine and an excess of beta-naphthol in aclosed vessel to a temperature of 200 C. for a prolonged period of time.

(14 hours or more), and extracting unreacted materials and by-productsby washing suc- 15 cessively with caustic alkali, hydrochloric acid,alcohol and ether. The yield obtained is quite low, about 40% in somecases. The yield has been improved by adding 1/3% of iodine to catalyzethe reaction, but the iodine is very expensiveand greatly increases thecost of the product, as well as introducing complications because of thenecessity of removing the catalyst from the product.

I have discovered that an excellent yield of very pure product may beobtained by heating a mixture of one molecular equivalent of p-phenylenediamine and a considerable excess, say a 50% excess, thatis, threemolecular equivalents, of beta-naphthol, to a temperature well over 200,preferably as high as 300 (1., and preferably in the absence of air. Thereaction may be represented by the following equation:

Application filed January 31,1929. Serial No.- 336,659.

molecular equivalents) of beta-naphthol. As the reaction vessel isheated the alcohol boils Off and may be condensed and recovered'forfurther use. p-phen'ylene diamine and the beta-naphthol in the sameratio as the original batch, and the process is conducted-from thispoint'on in the mannerdescribed above. I a 2 The method of thisinvention makes possible the production of the. dinaphthyl p-phenylenediaminein amuch shorter time than the previously known methods, andtherefore makes possible a greatly increased output from any givenequipment. The use of apparatusat atmospheric .pressure insteadof closedcontainers under pressure also reduces the required capital outlay. The"yield is increased to almost'100%, eliminating wasteful, troublesome'by products, the use of a catalyst is "eliminated, and the purificationprocess is'greatly simplified.

The vessel then contains the As a specific illustration of the processof I this invention, di-betarnaphthyl p-phenylene diamine is made on alarge'scale as follows:

{100 lbs..of beta-naphtholand 100 -lbs."of pphenylene diamine areplacedin an iron kettle equippedwith a tight-fitting cover and a condenser, The kettle is heatedby a direct flame. The reactingmaterialssoon melt anddissolve in one another. As the temperature reaches about220 C. water begins to be given off.

: OH 7 HO- NON r HzN-O-NHZ I V 21120 x The product is allowed to cool,is broken up, 40 and washed with alcohol, either methanol or ethanolbeing satisfactory. The alcohol dissolves the unreacted excess ofbeta-naphvthol, leaving a high yield of very pure symmetricaldi-beta-naphthyl p-phenylene di- '45 amine.

If desired, the alcohol solution containing the excess beta-naphthol ischarged into the :reaction vessel together with a fresh batch ofp-phenylene diamine and an approximately theoretical quantity (a slightexcess over two and the cake is washed with 25 gal. of cold alcohol. Thewashed product is dried in the air and is then ready to. use. The yieldis betterv than 98% of the amount calculated from the theory and theproduct is almost 100% pure.

The alcohol solution containing the excess beta-naphthol is returned tothe kettle, where the beta-naphthol may be recovered by distilling oilthe alcohol. If it is desired to make a number of batches, another 100lbs. of p phenylene diamine and 270 lbs. of beta-naphthol are added tothe alcohol solution in the kettle and the heating is repeated as in thepreparation of the first batch except that the alcohol which boils ofiat the beginning of the heating is condensed and saved;

I claim: W

1. The method of making symmetrical dibeta-naphthyl p-phenylene diaminewhich comprises heating a mixture of p-phenylene diamine and-a% excessof be-ta-naphthol at atmospheric pressure to a temperature of about 300(Lin the absence of a catalyst. I

2. The method of making symmetrical dibeta-naphthyl p-phenylene diaminewhich comprises heating a mixture of p-phenylene diamine and an excessof beta-naphthol to a temperature of about 300 C. in the absence of acatalyst, and Washing the excess of betanaphthol from the product withan alcohol volatile at normal temperatures.

3. The method of making successive batches of symmetricaldi-beta-naphthyl pphenylene diamine which comprises heating a mixture ofp-phenylene diamine and an excess of beta-naphthol to a temperature ofabout300 (3., dissolving the excess of betanaphthol from the productwith an alcohol volatile at normal temperatures, and adding the alcoholsolution of beta-naphthol to a later batch to .make up the desiredexcess of betanaphthol.

4Q The method of making successive batches of symmetricaldi-beta-naphthyl p-p'henylene diamine which comprises heating a mixtureof p-phenylene diamine and a 50% excess of beta-naphthol to atemperature of about 300 C dissolving the excess beta-naphth0l fromthefinely ground product with ethanol. and adding the ethanol solution ofbeta-naph tho-l to a succeedingbatch containingonly a slight excess 01":beta-naphthol.

In Witness whereof I have hereunto set myhand this 24th day of J anuary,l929.

.PAUL G. JONES,"

